Treiglad trwynol
- Before
- Prynais i fy car.
- After
- Prynais i fy nghar.
The possessive fy triggers nasal mutation: car becomes nghar.
Welsh
A Welsh grammar checker for Mac.
Paste Welsh into the free checker, or install the extension and write in Safari, Chrome, or Firefox. Cysill remains Bangor University's own product. Blas does not replace it inside Microsoft Word.
The editor on this page runs the website's mutation checker in your browser. The extension checks a wider set of spelling and grammar patterns. Typing alone does not send your text anywhere.
Try a mutation check
Live, local rules
Edit the text, inspect a suggestion and accept or dismiss it. This demo covers Irish and Welsh mutations, not every check in the extension.
Example: Prynais i fy car. — edit it or write your own.
Loading local rules…
Your text stays in this browser. The demo downloads language data and uses the website's local mutation checker; the extension has a separate, broader checking pipeline.
Soft, nasal, and aspirate mutation.
These are mutations the Welsh rules are written for. The editor offers a repair only when the website checker finds a missing mutation. No annotation does not mean the sentence is correct.
Treiglad meddal
- Before
- y merch
- After
- y ferch
The article y before a feminine singular noun soft-mutates merch to ferch. ll and rh do not take that mutation.
Treiglad llaes
- Before
- bara a caws
- After
- bara a chaws
The conjunction a before c, p, or t takes aspirate mutation. Before a vowel the conjunction is ac, not a.
What it checks
What the Welsh checker actually does.
The paste checker annotates selected mutations, verb forms, noun forms, and prepositional pronouns. The browser extension adds dictionary-backed spelling and writing mechanics. Neither one matches the whole of Cysill.
Mutations
Selected soft, nasal, and aspirate patterns, including fy, a feminine y, and a before c, p, or t. The extension can also flag a mutation that does not match its trigger.
Agreement
In the extension, selected adjective agreement, demonstratives, and quantifier mutation. The paste checker labels verb forms, noun forms, and prepositional pronouns it knows.
Spelling
Welsh spelling repairs in the extension are dictionary-backed. It does not guess one-letter typos in Welsh, because those guesses were too often wrong on real Welsh text.
English loanwords
The extension can flag some English loanwords that have a Welsh equivalent in its list. It does not stock a phrase-level calque list, and it will not rewrite a paragraph into more natural Welsh.
Register
A writing profile can flag some literary or colloquial markers. Ordinary modern written Welsh is not flagged merely for being colloquial.
Punctuation and style
The extension flags capitals, spacing, punctuation, and doubled words. Near-repetition polish is off for Welsh by default. The paste checker does not check mechanics.
North, south, and register
Welsh checking targets standard written Welsh. There is no Northern or Southern dialect switch. Some literary and colloquial markers can be flagged when register is set. The paste checker does not apply a register setting.
Where you can use it
On a Mac, the grammar checker is the browser. The Mac app is a different product.
On the web
Open the Welsh checker and paste a sentence. It runs in the browser and annotates supported patterns. It does not underline as you type, and it does not check spelling.
Safari, Chrome, and Firefox on Mac
This is the Welsh grammar checker for a Mac browser. Install it in Safari, Chrome, or Firefox and choose Welsh. The iPad version is not released. Passive checks stay on the device.
The learning apps
The iPhone, Android, and web courses teach Welsh. They are not the inline spell checker. The Mac app is dictation, not a system-wide Welsh spellchecker.
The course is separate from the checker.
Cysill and TextGens
Searches for a Welsh grammar checker on a Mac usually name Cysill, and sometimes TextGens. Blas has no published accuracy comparison with either.
Cysill
Cysill, from Canolfan Bedwyr at Bangor University, is an established Welsh spelling and grammar checker with its own desktop and online products. Blas does not install into Microsoft Word and does not claim Cysill's coverage. If you want Welsh checking in a Mac browser, the released Blas surface is the extension for Safari, Chrome, or Firefox.
TextGens
TextGens offers an online Welsh grammar checker. Blas also has a free paste checker and a browser extension that keeps passive checks on the device. That is a difference of where the checker runs, not a claim that one finds more errors.
Questions
Is Blas a Cysill alternative on Mac?
For Welsh checking in Safari, Chrome, or Firefox on a Mac, it is another place to check. It is not a Cysill replacement inside Microsoft Word, and the Blas Mac app does not check grammar system-wide. Cysill remains Bangor University's product.
What does the free Welsh checker on the website do?
It annotates selected mutations, verb forms, noun forms, and prepositional pronouns. It does not check spelling or punctuation, and a sentence with no notes can still be wrong.
Does it handle Northern and Southern Welsh?
There is no north or south switch. Checking targets standard written Welsh. A writing profile can flag some literary or colloquial markers. Ordinary modern written forms are not treated as errors just for being colloquial.
Does the Welsh checker run in Chrome?
Yes. The same extension runs in Chrome, Firefox, and Safari on Mac. Choose Welsh after you install it. The iPad version is not released.
How should I choose between Blas, Cysill, and TextGens?
Use Cysill if you want Bangor University's checker, including where it already fits a desktop or Word workflow. Use TextGens if you want that site's online checker. Use Blas if you want underlines in a Mac or desktop browser, or a free paste checker on this site. Blas does not publish a score against the others.
Will it replace a grammar?
No. For anything you publish, check geiriadur.bangor.ac.uk or a published Welsh grammar.
Check Welsh here, or in the browser you already use.
Paste a sentence into the free checker, or install the extension and choose Welsh.